1990 Ford F-150 questions.

Old 04-27-04, 03:48 AM
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1990 Ford F-150 questions.

Vehicle: 1990 Ford F-150, 4 wheel drive, 351 W, 4speed auto AOD trans. It has about 25,000 miles on a new Ford motor. About 130,000 on the vehicle itself.

Problems: It has a slight misfire or surging feeling at highway speeds. Seems to idle fine, when you rev it up in park it seems to be smooth, just when it's cruising along at highway speeds it seems as though it wants to surge backwards, or misfire. About 5000 miles ago one of the spark plug wires shorted out against the exhaust manifold, which of course made it run very bad. When I got home and found out what happened I replaced the wire. Could the shorted wire have damaged something in the distributer to make it miss like this? Does the distributer have a pick up coil that could easily be replaced?

The truck also has very worn ring and pinion gears. Is changing them a simple swap job or is it something better brought to a garage? It's been a few years since I have done that type of job and I'm not sure what's involved in it.

The gas mileage on this truck sucks too. I'm getting about 10-11 mpg. Could it get better than this? The truck has 3.55 gear ratio.
Old 04-28-04, 06:44 PM
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Lightbulb F-150

[SIZE=2]Your gas mileage should be slightly better than what it is. I would expect a 3-4 m.p.g increase to a more “normal” level. The ignition problem could have damaged other electronics in your vehicle, that is where I would start looking for a problem. I am not sure of the ignition system of that truck. The ring and pinion can be changed at home but there are a few tricks to it. If you are comfortable with it go for it! If it is a first time, it would be very nice to have some one who knows the ropes guide you though it. If you are not comfortable you will save yourself time and trouble and it will be safer, if you have it done. Sorry it took so long to get an answer! [/SIZE]

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